If you cast it in a non-town instance, go to town, and then go back, it stays on.
If you cast it in a non-town instance, and go to a different non-town instance, it stops.
Now, it seems that taking portals in a non-town instance (i.e. Piety's portal), it stops.

What is the actual intended behaviour for this skill?

"...we try not to be dicks." - Mark
"...i speke good englesh" - Rhys
"Bullshit, you get the game for free." - Qarl

192mb for a simple instance crash seems rather excessive. What else was included in this patch because I don't believe for a second that it was only a bug fix that somehow required almost 200mb of data to be downloaded.

192mb for a simple instance crash seems rather excessive. What else was included in this patch because I don't believe for a second that it was only a bug fix that somehow required almost 200mb of data to be downloaded.

A little more transparency would be nice.

Try reading the whole thread, this it's not even two full pages, and this is answered on the first. They accidentally included some changes to the shaders, which were not intended.